Search PubMed⌕ Search

Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 1,333 records · Page 74Linked to original sources
PubMed1991

[Effects of Ligusticum wallichii on the plasma levels of beta-thromboglobulin, platelet factor 4, thromboxane B2 and 6-keto-PGF1 alpha in patients with acute cerebral infarction].

By using ELISA and RIA to measure the levels of Beta-thromboglobulin (beta-TG), platelet factor 4(PF4), thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in plasma of patients with acute cerebral infarction, the authors found that the levels of beta-TG, PF4 and TXB2 in plasma had significantly increased (P less than 0.01), but the level of 6-keto-PGF1 alpha in plasma showed no change (P greater than 0.05). The results of the Ligusticum wallichii (Ligusticum) treatment to the test-group showed that the levels of beta-TG, PF4 and TXB2 in plasma had significantly decreased (P less than 0.01), and the level of 6-keto-PGF1 alpha in plasma had significantly increased (P less than 0.05). This suggested that the Ligusticum treatment could effectively inhibit the platelet activation in vivo and correct the TXA2-PGI2 imbalance in blood of the patients. In this study, some new approaches were explored to explain the mechanisms of Ligusticum for preventing and treating cerebral ischemia.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

[Pulmonary artery pressure estimated by Doppler echocardiography in patients with chronic obstructive pulmonary disease].

Doppler echocardiography and right heart catheterization were performed in 18 patients with COPD. The pulmonary blood flow pattern were analysed by the pulsed doppler flowmeter. The pulmonary artery acceleration time (PAT) showed significant inverse correlation with pulmonary artery mean pressure (mPAP) (r = -0.84, P less than 0.001) and pulmonary artery systolic pressure (sPAP) (r = -0.89, P less than 0.001). In fifteen of 18 patients, continuous wave doppler could be used to measure the maximal velocity of the regurgitant jet through the tricuspid valve (Vmax), and the right ventricle to the right atrium pressure gradient (PG) was calculated by means of simplified bernoulli equation (PG = 4V2max). PG correlated well with sPAP (r = 0.89, P less than 0.001) and mPAP (r = 0.92, P less than 0.001). We considered that doppler echocardiography was useful for noninvasive estimation of pulmonary artery pressure in patients with COPD.

Blood Pressure↗
PubMed1991

[Identification of twenty-eight species mycobacteria with their cellular fatty acids by capillary gas chromatography].

Cellular fatty acid (FA) of 28 species of mycobacteria were analysed by capillary gas chromatography (GC). There were more than sixty volatile FA before C12:0 have no any difference between species both in quality and quantity. The identification scheme of Mycobacterium based on cellular FA was presented here. According to this scheme, all the tested species could be divided into 8 groups by the FA peak height order of C18:1, C18:0 and TBSA which were quite stable; after that, 17 species (60%) might be identified to species level with help of some distinctive FA such as C19:0, C21:0. Most pathogenic bacteria could be separated by the scheme (M. tuberculosis, M. bovis and some complexes). This scheme was also demonstrated to be objective rationality by computer cluster analysis with cellular FA components.

Chromatography, Gas↗
PubMed1991

[Effects of nifedipine on pulmonary hypertension in patients with chronic obstructive pulmonary diseases--a comparison with oxygen administration].

We evaluated the effects of the calcium channel blocker nifedipine (Nf) as a vasodilator compared with oxygen administration on pulmonary hypertension and right ventricular performance in 15 patients with COPD. 1. Compared with baseline, sublingual administration of Nf (average dose 39.3mg) decreased mean pulmonary artery pressure (mPAP) and total pulmonary vascular resistance (TPVR) significantly. Cardiac index (CI) and oxygen transport were increased. PaO2 were unchanged and PvO2 were slightly increased after administration of Nf. 2. Compared with oxygen administration, Nf caused significant fall of TPVR. CI and oxygen transport increased. 3. In eleven of 15 patients, continued hourly Nf doses (from 20 to 60mg) produced a significant reduction in mPAP and TPVR. All patients but one did not produce symptomatic systemic hypotension. We considered that higher dose (30mg) of Nf was required to produce marked hemodynamic response in patients with COPD without any side effect.

Administration, Sublingual↗
PubMed1990

Potentiation of gamma-vinyl GABA (vigabatrin) effects by glycine.

Vigabatrin, because of its ability to increase brain GABA concentration, acts as an anticonvulsant on convulsive epileptic seizures and increases seizures in generalized non-convulsive epilepsy. Next to GABA, glycine is one of the most important inhibitory neurotransmitter amino acids. We studied the influence of glycine on the effects of treatment with vigabatrin in two rat models of generalized convulsive seizures and a rat model of spontaneous generalized non-convulsive seizures. Glycine (750 mg/kg i.p.) or vigabatrin (200 mg/kg i.p.), when given alone, provided partial protection against convulsive seizures, while combined treatment with the two drugs significantly suppressed the convulsive seizures in both the mercaptopropionic acid (MPA)-induced seizures and audiogenic seizures. In contrast to the response to treatment with each individual drug, the drug combination nearly abolished the appearance of isolated spikes on the EEG in MPA seizures. On the other hand, glycine also enhanced the aggravating effect of vigabatrin on spontaneous spike and wave discharges in a rat model of genetic absence epilepsy, whereas glycine or vigabatrin alone, at the above doses, produced only a slight, non-significant increase in spontaneous spike and wave discharges. The GABA-glycine interaction is the first example of a synergistic action of two inhibitory neurotransmitters on seizure-related pathological discharges.

3-Mercaptopropionic Acid↗
PubMed1990

The GABAergic nigro-collicular pathway is not involved in the inhibitory control of audiogenic seizures in the rat.

Involvement of the GABAergic nigro-collicular pathway in the control of audiogenic seizures was examined in genetically sensitive rats by studying the effects of bilateral injections into the substantia nigra of muscimol, a gamma-Aminobutyric acid (GABA) agonist, and those of bilateral injections into the superior colliculus of picrotoxin, a GABA antagonist, and of muscimol. Microinjections of muscimol (20-80 ng/side) into the substantia nigra and microinjections into the superior colliculus of picrotoxin (20 and 40 ng/side) both failed to suppress audiogenic seizures. Following injections into the superior colliculus, audiogenic seizures were in fact facilitated by picrotoxin and suppressed by muscimol. These results suggest that the nigro-collicular GABAergic pathway is not involved in the inhibitory control over audiogenic seizures. Conversely, a different GABAergic mechanisms may be involved in the superior colliculus in the control of this form of epilepsy.

Acoustic Stimulation↗
PubMed1990

Myelin formation following transplantation of normal fetal glia into myelin-deficient rat spinal cord.

Structurally normal myelin sheaths develop in the spinal cord of juvenile myelin-deficient rats (mdr) 11 days after transplantation of normal fetal spinal cord fragments or cultured cells that do not yet express galactocerebroside. Cultures result in more extensive myelin formation, and in both cases the myelin that forms is located primarily at or near the site of transplantation. Myelin formation also occurs after transplantation of postnatal donor tissue, but the extent diminishes with donor age, and none was seen after transplantation of adult donor tissue over the two-week period studied. Injection of killed tissue, tissue derived from mouse donors or an extract of myelin also did not lead to myelin formation. The results imply that myelin formed in the host following transplantation was generated by oligodendrocytes newly differentiated from donor precursor cells rather than by donor oligodendrocytes that were already mature at the time of transplantation or by host oligodendrocytes that took up components of the injected material. We conclude that exogenous fetal glial cell precursors are able to survive, differentiate and form myelin in the environment of the juvenile mdr spinal cord.

Aging↗
PubMed1990

Influence of hypothyroidism and the reversal of hypothyroidism on hemodynamics and cell size in the adult rat heart.

Hypothyroid-induced atrophy of cardiac myocytes was examined in adult female rats in an effort to correlate hemodynamic and cellular changes associated with this disorder. Additional rats were studied 6 weeks after discontinuing antithyroid treatment to determine if structural and functional changes were completely reversible. To induce hypothyroidism, rats were injected daily with propylthiouracil (PTU) for 4 weeks. Control animals were injected similarly with Tris buffer. At the end of the treatment period, hemodynamic measurements were made prior to obtaining isolated myocytes. Cell volume, length, and cross-sectional area were obtained from the septum, and left and right ventricles of treated and untreated rats. After four weeks treatment with PTU, body weight was unchanged but heart weight was significantly reduced by 24%. Characteristic hemodynamic changes associated with hypothyroidism in the rat were noted (eg. reduced heart rate, cardiac output, dP/dtmax, and ventricular pressure). Cell volume was significantly smaller in hypothyroid rats primarily due to a reduction in myocyte cross-sectional area. The hemodynamic and cellular response to hypothyroidism was similar in the right and left ventricle. Six weeks after discontinuing PTU treatment, cellular and hemodynamics changes had returned to normal. It was concluded that hypothyroidism caused a true cardiac atrophy which was reversible. Reduced myocyte cross-sectional area was responsible for most of the myocyte atrophy.

Animals↗
PubMed1990

Nonlinear dynamic behavior of cardiac oscillators.

By studying a mathematical model of the effects of brief current impulses on the oscillation of cardiac cells, we have simulated the phase transition curves of the oscillators. This has permitted discussions of the interactions of two coupled sinus oscillators and the periodic stimulation of one ventricular oscillator. The results have been compared with findings from the normal electrocardiogram and applied to explain the mechanisms of some arrhythmias.

Arrhythmias, Cardiac↗
PubMed1990

Involvement of the nigral output pathways in the inhibitory control of the substantia nigra over generalized non-convulsive seizures in the rat.

Activation of GABAergic transmission within the substantia nigra has been shown to suppress several forms of generalized seizures in experimental models of epilepsy. More especially, such pharmacological manipulations suppress spontaneous and chemically-induced generalized non-convulsive seizures in the rat. The aim of the present study was to examine the role of the dopaminergic and GABAergic thalamic and collicular nigral outputs in this antiepileptic effect. For this purpose, we examined the effects of output destruction on the antiepileptic effect of intranigral injections of a GABA agonist or pharmacological blockade of the neurotransmission at the nerve terminal level in rats with spontaneous absence seizures. After selective destruction of dopaminergic neurons within the substantia nigra with 6-hydroxydopamine (5 micrograms/side) or hemisection of the ascending nigral output, bilateral intranigral injection of muscimol (2 ng/side) still significantly suppressed generalized non-convulsive seizures. Bilateral lesioning of the ventromedial nucleus of the thalamus did not abolish the antiepileptic effects of intranigral muscimol (2 ng/side) and the GABA antagonist, picrotoxin, when given into this thalamic nucleus (10 ng/side) also failed to induce suppression of spike and wave discharges. The antiepileptic effects of intranigral injection of muscimol (2 ng/side) was reversed by bilateral electrolytic lesions of the superior colliculus. Blockade of the GABAergic transmission at this level with picrotoxin (40 ng/side) significantly suppressed generalized non-convulsive seizures. Finally, excitation of collicular cell bodies with low doses of kainic acid (4 and 8 ng/side) also resulted in a suppression of spike and wave discharges. These results demonstrate that the GABAergic nigrocollicular pathway is critical for the inhibitory control of the substantia nigra over generalized non-convulsive seizures. The data further suggest that antiepileptic effects observed following potentiation of GABAergic transmission in the substantia nigra result from a disinhibition of collicular cell bodies.

Animals↗
PubMed1990

Suppression of spontaneous generalized non-convulsive seizures in the rat by microinjection of GABA antagonists into the superior colliculus.

Intranigral injections of GABA agonists suppress spontaneous and chemically induced generalized non-convulsive seizures in the rat. In order to examine whether the GABAergic nigrotectal pathway could be involved in this suppression, bilateral injections of GABA antagonists were performed in the superior colliculus of rats with spontaneous generalized non-convulsive seizures. Bilateral microinjections into this structure of the GABA antagonists picrotoxin (20 and 40 ng/side) and bicuculline methiodide (5 ng/side) suppressed spike-and-wave discharges for 40 min and 20 min post injection, respectively. Unilateral injections of picrotoxin (40 ng) into the superior colliculus as well as bilateral injections of a GABA agonist (muscimol; 80 ng) did not induce significant modifications. These results show that blockade of the GABAergic transmission at the level of the superior colliculus results in a suppression of generalized non-convulsive seizures. These data support the hypothesis that the suppressive effect of intranigral injections of GABA agonists over generalized non-convulsive seizures involves, at least in part, the nigrotectal GABAergic pathway.

Animals↗
PubMed1990

Prevalence survey of cytomegalovirus infection in children in Chengdu.

Cytomegalovirus (CMV) is a common worldwide perinatal infection. Although usually asymptomatic, it may cause deafness in up to 15% of these infants. A cross-sectional study was performed to determine the age-specific prevalence of CMV seropositivity in Chinese children and to determine if any risk factors for infection could be identified. In a two-stage sampling procedure, nine districts were randomly selected from 70 citizenship districts in Chengdu, Sichuan Province, People's Republic of China. Then, 1,950 households were randomly selected from 11,886 households and interviewed. Blood was obtained from all children aged less than seven years and assayed using an enzyme-linked immunosorbent assay method. A subgroup of sera was retested at the research laboratory and also sent to the National Reference Laboratory in Beijing. Kappa values for the test agreement with the reference laboratory and retesting within the study laboratory were 0.94 and 0.86, respectively. Seropositivity averaged 52% in those aged less than one year and 60% in those between four and seven years. A higher rate of seropositivity was observed in urban versus rural children (odds ratio (OR) = 2.55), breast feeding in urban areas only (OR = 1.87), and day care versus home care setting (OR = 1.59). High CMV seroprevalence, even in the first year of life, was observed in this population of well children in Chengdu, China. An association was observed between seroprevalence and residence, method of feeding, and day care attendance.

Bottle Feeding↗
PubMed1990

On the relationships between rural labor productivity, family investment in education, and population quality.

The authors consider "the relationships between labor productivity and population quality in order to demonstrate the importance of economic development, and of improving population quality in rural areas. This study is made on the basis of surveys conducted in 1979 and 1986 on the age-specific VP and VC [volume of production and volume of consumption] in certain areas of Jiangsu Province [China]." Population quality is defined primarily in terms of the educational status of the labor force.

Asia↗
PubMed1990

[Effects of Ligusticum wallichii on the plasma and CSF levels of dynorphin A1-13 in rabbits under acute experimental cerebral ischemia].

By occluding the bilateral carotid arteries of rabbits to produce bilateral partial cerebral ischemia, and by using radioimmunoassays to measure the levels of dynorphin A1-13 like immunoreactivity (ir-Dyn A1-13) in plasma and cerebrospinal fluid (CSF), the authors find that the levels of ir-Dyn A1-13 in plasma and CSF have significantly increased (P less than 0.01) after cerebral ischemia appears. The result of the Ligusticum wallichii Franch (Ligusticum) pretreatment to the test-group shows a definite improvement of the changes of ir-Dyn A1-13 levels in plasma and CSF. The severity of brain ischemic damage and neurologic dysfunction in Ligusticum-treated animals is lighter than that of saline-treated group, too. In this study, some new approaches are explored to explain the pathophysiology of cerebral ischemia and the mechanisms by which Ligusticum prevents and treats cerebral ischemia.

Animals↗
PubMed1990

[Hemilaryngectomy for squamous cell carcinoma of the larynx with fixed cord].

This retrospective clinicopathologic study is to determine whether true vocal cord fixation produced by epidermoid carcinoma of larynx is an absolute contraindication of treatment by hemilaryngectomy. Serial sections of 19 hemilaryngectomy specimens were re-examined and clinical records of each patient reviewed. The microscopic view revealed that true vocal cord fixation was caused by the vocalis muscle invasion in 16 of the 19 patients. "Positive margins" concerned with recurrences were present in 4 cases. There were 3 local recurrences. The five-year survival rate in the series demonstrates a 68 percent (13/19) determinant survival rate and a 76 percent (13/17) actual survival rate. The results suggest that careful attention to the exact anatomical extent of the tumor should determine its surgical resectability. True vocal cord fixation itself should not exclude the possibility for total laryngectomy.

Adult↗